Hydraulic lift



PATENIED nEm 519m SHEET 1 0F 4 Clifford 71 Dean? INVIENTOK PATENTEUBEBISISIB 3547.225

' sum 2 0r 4 wiffard FT Dmve IN VIENTOR.

PATENTEUUEE SHEET 3 [1F 4 (Iiiffard 7;

INVENTOR.

HYDRAULIC LIFT This invention relates to working platforms and more particularly to a mobile type of working platform selectively elevated to any desired height by power operated mechanism.

Power elevated working platforms are of course well known and commonly supported by a boom mechanism from a vehicle bed. The present invention however is concerned with the provision of an elevatable working platform of greater versatility than those heretofore available. Accordingly. an important object of the present invention is to provide a working platform supported on a wheeled mobile frame to form a unit which is self-contained. The working platform unit is thereby capable of being utilized at locations ordinarily inaccessible to other working platforms both inside and outside building en closures. Furthermore, despite its mobility, the platform unit of the present invention has the requisite stability necessary for reliable and safe use. Ample working space is also provided in congested areas by means of the platform unit which nevertheless often occupies less space than a ladder. Also, the economic design and arrangement of the component parts of the working platform unit compares favorably in investment and replacement costs with ladder and scaffold arrangements. In accordance with the present invention, the working platform unit involves a mobile base frame assembly having adjustable outrigger components providing lateral stability. The

platform assembly is supported on and connected to the base frame through a lazy tong mechanism accommodating vertical elevation of the platform by means of hydraulic piston assemblies carried by the lazy tong mechanism itself. .The platform is provided with a guard rail having a gate rail member pivoted at one end of the platform to an end post- Power for operating the hydraulic piston mechanisms is furnished from a power struction and operation as more fully'hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 is a perspective view showing one form of working platform unit constructed in accordance with the present invention in an elevated condition.

FIG. 2 is a perspective view showing the working platform unit in a collapsed condition.

FIG. 3 is a transverse sectional view taken substantially through a plane indicated by section line 3-3 in FIG. 2.

FIG. 4 is a longitudinal sectional view taken substantially through a plane indicated by section line 4-4 in FIG. 3.

FIG. 5 is an enlarged partial perspective view showing the guard rail gate facility associated with the working platform unit.

FIG. 6 is a partial sectional view taken substantially through a plane indicated by section line 6-6 in FIG. 1;.

FIG. 7 is an enlarged partial sectional view taken substantially through a plane indicated by section line 7-7 in FIG. 3.

FIG. 8 is a hydraulic-electrical circuit-diagram illustrating the control system associated with the present invention.

FIG. 9 is a perspective view of another form of working platform constructed in accordance with the present invention.

Referring now to the drawings in detail, FIGS. 1 and 2 illustrate one form of working platform unit generally referred to by reference numeral 10. In the collapsed condition illustrated in FIG. 2, the unit 10 may be moved to anydesircd location either inside or outside a building enclosure below some elevated working station. The unit is accordingly supported on the ground by a wheeled base frame assembly generally referred to by reference numeral I2 on which the working platform assembly 14 is supported. When the base frame assembly is in a desired location, it is stabilized by adjustable outrigger components 16 as shown in FIG. I before the platform assembly 14 is raised to an elevated position by means of a pair of hydraulic piston assemblies 18 associated with an extensible lazy tong mechanism generally referred to by reference numeral 20 which interconnects the platform as sembly 14 with the base frame assembly 12. Power for operating the hydraulic piston assemblies in order to raise or lower the platform assembly is derived from a self-contained power supply generally referred to by reference numeral 22 which is fixedly mounted on the base frame assembly. Control over the power supply is exercised through a control box 24 on the platform assembly. An extensible electrical cable 26 interconnects the control box with the power supply 22 as will be hereafter described in detail.

The base frame assembly 12 is constructed from a lower rectangular frame 28 which pivotally mounts wheel assemblies adjacent the corners thereof at the forward end 32 and the rear end 34. An upper rectangular frame 36 is mounted in fixed spaced relation above the lower frame 28 to which it is connected by a plurality of spaced frame separators 38. An upwardly foldable step 40 is pivotally connected to the forward end 32 of the base frame assembly by means of step hinge brackets 42 secured to and projecting forwardly from the forward end of the upper frame 36. Adjacent the forward end, the lower frame 28 is supported above the ground by a pair of wheels 44 rotatably mounted by rigid brackets 46. Swivelly mounted caster brackets 48 on the other hand rotatably mount the wheels 50 adjacent the rearend 34 of the base frame assembly. Also mounted adjacent the corners of the base frame assembly at the forward and rear ends are four vertical adjustment sleeves 52 secured as by welding by the plates 54 to the upper and lower frames 36 and 28 The outrigger components 16 are received within the vertical sleeves 52 in angularly and vertically adjusted positions. A thumbscrew 56 is associated with each sleeve 52 in order to lock the vertical shank portion 58 of each outrigger component 16 in an adjusted position. A laterally extending, downwardly inclined arm 60 extends from each vertical shank portion 58 and is connected at a remote end to a foot element 62 from which a serrated rubber pad 64 projects into engagement with the ground. The outrigger components 16 may accordingly be adjustably mounted in verticallyand angularly adjusted, positions to hold the base frame assembly ata given location and provide the requisite lateral stability for the working platform unit. The outrigger components as well as the rectangular frames of the base frame assembly may be made of tubular metal dimensioned to have the requisite strength necessary to sustain the loads for which the platform unit is designed.

The lazy tong mechanism 20 is pivotally connected to the base frame assembly about a fixed axis adjacent the forward end 32, while it is slidably connected to the base frame assembly adjacent the rear end 34. Thus, a pair of lowermost links 66 of the lazy tong mechanism 20 are provided with pivots 68 at their lower ends as more clearly seen in FIG. 6 extending into the upper frame 36 to which the lazy tong mechanism is pivotally connected. The lowermost links 66 are pivotally connected with crosslinks 70 at intermediate pivots 72. The links 70 at the lower rear ends thereof are provided with rollers 73 as more clearly seen in FIG. 7. The rollers 73 are slidingly received within channel formations in the upper frame 36 and in a guide track member 74 as more clearly seen in FIG. 3 extending forwardly from the rear end 34 of the base frame assembly. As shown in FIG. '7, a bottom wall 76 bridges the guide member 74 and the upper frame 36 and is provided with an upwardly extending portion 78 mounting a limit switch 80 adapted to be engaged by one of the links '70 in the lowered position-of the lazy tong mechanism as shown in FIG. 2. As will be explained hereafter in detail. this limit switch 80 forms part of the control system for controlling operation of the hydraulic piston devices 18.

The crosslinks 66 and 76 forming the lowermost link sections of the lazy tong mechanism, are pivotally connected at their upper ends by end pivots 82 and 84 to intermediate crosslink sections consisting of the cross links 86 and 88 interconnected by intermediate pivots 90 as in the case of the lowermost crosslinks 66 and 70. The intermediate links 88 may also be provided with braces 92 to resist bending. Also, the pivotally interconnected links of the lazy tong mechanism disposed on either lateral side of the unit are fixedly spaced apart by spacing bars 94 at a plurality of locations. A crossbar 96 also spaces the intermediate links 86 on one side of the intermediate pivots 90*and 72 opposite the forward end of the base frame assembly and is connected to the piston rods 98 associated with each of the hydraulic piston devices 18. The piston rods 98 and the crossbar 96 to which they are connected, thus constitute a ram extended from and retracted into the hydraulic cylinders 1110. The lower ends of the cylinders are pivotally mounted between the lowermost links 66 adjacent the pivots 68 by means of the tubular pivot rod 102, as more clearly seen in FIGS. 1 and 6. Accordingly, fluid under pressure supplied to the lower ends of the cylinders 100 is operative to extend the piston rods 98 causing upward elevation of the platform assembly through the lazy tong mechanism, while venting of the lower ends of the cylinders will effect controlled lowering of the working platform assembly. The uppermost links 104 of the lazy tong mechanism are therefore pivotally connected about fixed pivots 106 to the platform assembly adjacent the forward endthereof while the uppermost crosslinks 108 are slidably connected to the platform assembly through rollers 110 as more clearly seen in FIG. 3. 1

The platform assembly 14 is constructed of a tubular rectangular frame 112 forming guide channels adjacent the rear ends thereof laterally spaced from guide members 114 for guidingly receiving the guide rollers 110 as shown in FIG. 3. The rectangular frame 112 supports a floor 116 suitably braced by brace members 118 connected'to the rectangular frame 112'below the floor. At least fourposts 120, 122, 124 and 126 are connected to and extend upwardly from the rectangular frame 112 adjacent the corners thereof. The posts form part of a guard rail assembly including the side rails 128 and 130 interconnected-at the rear end by a fixed end rail 132, the latter rails being secured to the upper ends of the posts. At the forward end of the platform assembly, a gate rail 134 is pivotally connected to the side rail 128. As more clearly seen in FIG. 5, the forward end of the side rail 128 includes a hinge cavity portion 136 receiving the hinge core 138 projecting from a right-angle portion of the gate rail 134 opposite the reduced diameter portion 1411 adapted to be received within a semicylindrical cutout section 144 of the side rail 130 secured to the upper end of post 122. Aligned openings 146 are formed in the portion 140 of the gate rail and the cutout section 144 of the side rail 130 in order to receive a lockpin 148 secured by a flexible chain 150 to the side rail 130. Thus, the gate rail 134 may be pivotally displaced upwardly as shown by dotted line in FIG. in order to permit entry of an operator into the platform assembly in its lowered position shown in FIG. 2. The step 40 facilitates entry of the operator onto the platform after which the gate rail 134 is closed and secured in place by the pin 148.

A larger version of the platform unit generally denoted by reference numeral in FIG. 9 is also contemplated. The base frame assembly in this version of the invention is supported above the ground by four relatively heavier traction wheels 152. The larger unit 10' unlike the smaller version hereinbefore described, is adapted to be transported from one location to another by towing. Toward this end, the front end of the base frame assembly is provided with a hitch mechanism 154 while a stepladder section 156 is secured to the base frame assembly on one side of the hitch mechanism extending upwardly therefrom in order to permit an operator to step up onto the platform assembly in its lowered position as illustrated in FIG. 9. Also, in view of the dimensionally larger and heavier design of the unit 10'. the four ground-em gaging outrigger components are eliminated in favor of a pair of upwardly foldable, wheeled outrigger assemblies 158. As an optional feature, the larger version 10 may also be selfpropelled. As to the other more basic structural and operational attributes, the larger unit 10 is similar to the smaller version 10 hereinbefore described and illustrated in FIGS. 1 through 7.

Referring once again to the working platform unit 10 and in particular to FIGS. 3 and 4, it will be observed that the base frame assembly carries the power supply 22 which includes an electrical source of energy in the form of a set of batteries 160 adapted to be recharged from any conventional source of electrical energy by means of a battery charger 162 adapted to be plugged into an available source of electrical energy through the cable 164. The set of batteries 160 may accordingly be maintained in a charged condition for supplying electrical energy to a DC pump motor through a solenoid starter 166 and to a normally closed solenoid valve assembly 168. Thus, a fluid reservoir 170 may be pressurized in order to supply fluid under pressure from the pressure outlet 172 to the lower ends of the cylinders for elevating the platform assembly. The upper ends of the cylinders are connected to a vent return fitting 174 of the reservoir 170 which is also provided on the top thereof with a breather fitting 176. The foregoing components of the power supply are fixedly mounted on the base frame assembly in any suitable manner with the pressure and vent fittings 172 and 174 of the reservoir located adjacent the forward end of the base frame assembly close to the lower pivoted ends of the cylinders 100 so that short flexible hose connections may be utilized for accommodating a minimum amount of displacement of the cylinders relative to the stationary reservoir during elevating and lowering movement of the cylinders. By controlling operation of the pump motor and the normally closed solenoid valve assembly 168, through the control box 24, the operator on the platform assembly is able to effect both elevation and lowering of the platform assembly. The control box is mounted on the post 122 through which the cable 26 extends.

The various components of the power supply 22 hereinbefore described together with the components within the con trol box 24 interconnected with the power supply through the electrical cable 26, form part of a control system as'depicted in FIG. 8. The batteries. connected across the output charging terminals of the battery charger 1 62 supply energizing current to the relay coil 178 of the starter through an energizing circuit completed when the pushbutton switch 180 at the control box is actuated. The relay energizing circuit is established through conductor 182 from the output terminal of batteries 160, the bridged contacts 184 and 186 and the conductor 188 connected to contact 1786. Upon energization of relay 178, relay switch 208 is closed to complete a motor energizing circuit through the normally closed contacts of the down switch 210 to operate pump 206 through the pump motor 196. While up switch 180 is actuated the normally bridged contacts 190 and 192 are opened so that valve solenoid 212 remains deenergized and valve 163 closed. The reservoir therefore is pressurized by the pump 202 at a high pressure since return line 206 is blocked by closed valve 168 to pressurize line 172 causing extension of the piston rods 98 from the cylinders 100 to elevate the platform.

After the platform has been elevated from its lowered position, the limit switch 80 is released and closes to complete a relay holding circuit through the normally opened relay switch 198 closed by energization of relay coil 178. Thus, upon release of the up switch 180, the relay coil 178 remains energized to maintain the pump motor 196 operating through relay switch 208. Also, upon release of the up switch, contacts 120 and 192 are bridged to complete an energizing circuit through relay switch 198, limit switch 80, conductor 138 and conductor 194 for the valve solenoid 212 to open the valve 168. A fluid circulating path is thereby established between the pump 200 and the reservoir 1711 to maintain a reduced pressure therein sufficient to hold the platform in its elevated position through the piston devices 18. By again actuating the up switch to deenergize the valve solenoid 212 and close valve 168, the platform may be further elevated to the limit of its movement.

In order to lower the platform from an elevated position, the down switch 210 is actuated to interrupt the motor circuit. The reduction in pressure in the reservoir resulting therefrom will permit controlled retraction of the piston rods into the cylinder and lowering of the platform until the down switch is released to resume operation of the pump. if the platform is lowered to its completely lowered position opening the limit switch 80, the relay holding circuit for the relay coil 178 is interrupted thereby causing its deenergization and opening of the relay switches 198 and 208. The valve l68 therefore closes and operation of the pump stops to shut down the operating system. The limit switch 80 therefore operates as a safety feature to prevent continued operation of the pump and drain on the batteries 160 while the platform assembly rests in its fully lowered position on the base frame.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

I claim:

1. A load elevating apparatus comprising a base frame, a platform supported on the base frame, a lazy tong mechanism interconnecting the base frame and the platform for maintaining the platform substantially parallel to the base frame during movement thereof, and power operated means mounted exclusively by the lazy tong mechanism for'movement of the platform relative to the base frame between elevated and lowered positions, said power operated means including a fluid piston device having a movable ram, said lazy tong mechanism including a plurality of crosslink sections pivotally connected to each other, means pivotally connecting said crosslink sections to the platform and the base frame at said one end thereof and means slidably connecting said crosslink sections to the platform and the base frame adjacent an end opposite said one end, anchor means pivotally connecting the piston device to one of the crosslink sections adjacent said one end of the base frame, said ram being pivotally connected to another of the crosslink sections adjacent said opposite end.

2. The combination of claim 1 including a pair of end posts mounted on the platform at said one end thereof, an end rail pivotally mounted on top of one of the end posts, and means mounted on top of the other of the end posts for releasably holding the end rail in a closed position.

3. The combination of claim 2 including power supply means fixedly mounted on the base frame and connected to the power operated means and control means mounted on said other of the end posts for selectively controlling the supply of energy from the power supply means to the power operated means, said control means including a flexible cable extending through the other of the posts and from the platform to the power supply means on the base frame in all positions of the platform.

4. In a load elevating apparatus having a base, a platform and transversely spaced, lazy tong linkages between the base and the platform, means for actuating the linkages including a pair of fluid operated piston devices having piston rods extending therefrom and spacer means interconnecting the piston rods with the linkages in transversely spaced relation to each other for simultaneously actuating the linkages, said linkages having horizontally fixed ends secured to the base and the platform and horizontally movable ends slidably mounted on the base and the platform and anchor means pivotally connecting the piston devices to the linkages adjacent the horizontally fixed ends, said spacer means being connected to the linkages adjacent the horizontally movable ends vertically spaced above the anchor means. 

